Pick-up device



l@ operation, that is, can be adapted tor pro-v Till lill

Patented llico. 27, 1927.

UNITED ,sT-A

1,654,203 TES PATENT oFFicE.

RTHUR :PRIMROSE YOUNG, 0F KEILWORTH, AND JOSEPH HUTT, UF CUVE-TRY, ENGLAND, ASSIGNQRS T0 GENERAL ELECTRIC COMP-ANY, A. CRIORATN F NEW YORK.

' roicnr ouvaton.

application led January 14, 1927, Serial No. 161,132, and in Great Britain January 9, i926.

Uur present invention relates to gramo. phones and like talking machines and also to picleup or sound producing apparatus otthe kind wherein the vibrations ot a `,lramophone or like stylus are converted into corresponding electric oscillations, which can then be passed through headphones. or loud-speakers, 'when required. These appa ratus, is well known, .arereversible inA ducing record cuts.

The main object vctour invention is the provision ol" pick-up apparatus having substantially aperiodic stylus-lever, and to this end the lever is mounted without any sprinir control, and damping means are provided for suitably restraining the movement .ot the same. The damping arrangement may consist of a chamber the size ot which is adjustable and which contains t' aI A non-elastic damping material, such as cotton wool, with a portion of the stylus lever 'or a member rigidly secured thereto located in the chamber. lAny lequivalent arrange.

ment may be used; for instance, a portion of the stylus-lever, preferably an end extendlng away from the needle end., or a mem ber rigidly `secured thereto, may be ar-y ranged between two adjustable washers of non-elastic damping material.

@ur invention further comprises the combination oit a stylus-lever'mainly' or entirely supporting an operable member, that is, diaphragm, coil, armature or the like, with damping means associated therewith which are nonresilient in their elect. In the case ol sound producing apparatus said operable member is preferably a light, rigid, conically-shaped diaphragm, connected at its apen to the stylusand with its periphery only loosely connected to the fixed structure it at alln lliccording to a further feature ot our in vention, apparatus for converting the mechanical vibration of a gramophone or lilte stylus into equivalent electric oscillations, or vice versa, including a conductor or coil adapted to be moved in a uniform magnetic tield in accordance with the vibrations ot the stylus, is arranged so that the center point oli the conductor or coll is almost exactly above the tulcrum oi the stylus-lever; Vilith.v such an arrangement tor a limited moinement ot the needle, the movement of the coil` or conductor substantially horizontal, and, herelore, the use of means vfor specially centering the coil, which would probably introduce a resilient restoring force, is ob ,viated A rr a n ge ments to apparatus for comfertinp,l the sound impressions ol a gramophonc or lilterecord into corresponding electric oscillations, are shown in lIllhgs. l, 2.V 3 and l of the accompanying dcawings, which are sectional or part sectional views, Figs. l, 2, and El boing,r side views oi the arinngemcntsof Figs. l, 2 and 3. Lilie reference numerals are used to indicate similar parts.

Referring to the drawings, and iirst to Figs. l and l, this construction comprises a pair olf approximately C-shaped magnets 1l arranged in one plane with their air gaps lladjacentone to another. Preferably the inainiriortions 13 ol' each magnet are permane'nt bar magnets of cobalt steel, the end limbs 14e adjacent the air gaps being ol' sott iron. These two C-shaped magnets are suitrod 16 is provided with any suitable device 21 for receiving and holding the stylus needle 22. The upper ertreniity 23 ot the rod is located in a chambcr'rll conveniently formed between the two magnets and lilled with a suitable damping material, such as cotton-wool, and a screw plug 25 maybe provided for closing,n bne end of the chamber 2a and for adjusting theipressure ci the paclringf. I

, In the arrangement of lfig'f, 2 and ila the type of apparatus illustrated includes a pot shaped magnetic circuit ll having inner and outer pole-pieces 2G and 2i", respectively, with an annular air gap l2 between. The coil 'l5 now oi annular lorm is located in the 'air-gap l2 and secured to the stylus lever 16 approximately halt way up. The stylus-lever 16 is bentas a hellbraun, the

lor applying; our invention lower portion being fulcrumed in the cups able means being provided for clamping 'the'A 18, almost exactly beneath the center point ofthe coil 15, carried by the bracket 28 ixedto the magnetic structure. As in the previous case, the lower extremity of the stylus-lever` is adapted vto receive and hold the needle 22 and the Lupper extremity 23 is located inv an adjustable damping chamber 24. g

Figs. 3 and 3a show a moditieationof the arrangement describedy in the preceding paragraph in which the stylus-lever 16 does not extend upwardly appreciably beyond the center of the coil 15. Secured to vthestyluslever is a bolt 29 perpendicular thereto which carries a plate` 31 or the equivalent located between two adjustable washers 32,'any suit- Washers against the plate and for reducing or increasing the pressure between the washers and, the plate. These means are here shown as being .constituted by the plates 33 and 34 interconnected bythe screws 35, plate will readily be understood that the iiux4 passes radially. between the pole pieces 26 and '27 through the annular air gap 12. In the arrangement illustrated by Fig. 4, the innerpole piece'27- is slotted at one or more places' longitudinally as by saw-cuts and y strips of a suitable material 42, for instance,

' it oscillates. It will be noted that although rubber, are located'fin the slots and'arranged to extend radially'therefrom suiiciently. to

engage the interior of the former carrying the coil 15l Preferably the slots are arran ed symmetricallyl around the periphery of t e inner pole piece in order to avoid any tendency towards displacing the coil 15 when the strips 42 may be made from elast-ic material, yet theyv exert no spring'eontrol on the moving elements in the direction of their motion, butl serve -only v to damp the movement of the saine. If the-coil were wound internally of the former it might be desirable to arrange the material 42 in the `face of the outer pole piece 26, inordrthat the non-magnetic body portion 44 and the Acasing 38 together.

In'giamophones and the like provided With non-resilient damping devices according to the invention, the diaphragm may be of such size as to give the requisite volume of .sound Without the use of an amplifying sound horn. JAlternatively a baille may be yment of said member, and means operable to adjust the pressure between said material and said member.

2. A-pick-up device comprising a magnet provided with pole pieces arranged to form an air gap, a pivoted member, a coil suplported by said member and arranged to be moved to and fro in said air gap, means arranged to produce a substantially nonresilient restraint on the movement'of said member and means for adjusting thepressure between said means and said member.

3. A pick-up device comprising a magnetI provided with pole pieces arranged to form a circular air gap, a pivoted member, a coil supported by said member and arranged to be moved to and fro in said air gap, a body of-` cottonswool arranged to restrain the movement of said member, and means for adjusting-the pressure between said body and said member.

.4. A pick-up device comprising a magnet,

. a pivoted member, 'a coil supported by said memberrand arranged to be moved Vbetween the poles of saidmagnet, a body of cotton` wool arranged to restrainthe movement of said member, and means operable to adjust 4the pressure between said material and said member. y j g In Witness whereof, we have hereunto set -our hands this 29th day. of December, 1926.

ARTHUR rRiMRosE YOUNG. JOSEPH HUTT.

iio 

